According to a study published in the New England Journal of Medicine, women exposed to diethylstilbestrol (DES) before birth have an increased risk of vaginal cancer, cervical precancers, and breast cancer. These women also have an increased risk for a wide range of reproductive problems.
Diethylstilbestrol is a synthetic estrogen that was prescribed to pregnant women between 1940 and 1971. The drug was used to reduce the risk of miscarriages, though later studies indicated that it most likely had no effect on miscarriage risk.
In 1971 a study reported that girls born to women who had used DES during pregnancy (DES daughters) had an increased risk of developing a rare type of vaginal cancer known as clear cell adenocarcinoma. Researchers have continued to conduct studies of DES daughters in order to assess longer-term health risks.
The current study collected information from 4,600 DES daughters and 1,900 women who had not been exposed to DES.
The following medical conditions occurred more frequently in DES daughters than in women who had not been exposed to DES:
- Clear cell adenocarcinoma of the vagina (40 times more common in DES daughters)
- Neonatal death (8 times more common)
- Pre-term delivery (4.7 times more common)
- Loss of 2nd trimester pregnancy (3.8 times more common)
- Ectopic pregnancy (3.7 times more common)
- Stillbirth (2.4 times more common)
- Infertility (2.4 times more common)
- Early menopause (2.4 times more common)
- Precancerous changes to the cervix (2.3 times more common)
- Breast cancer (1.8 times more common)
- First trimester miscarriage (1.6 times more common)
- Preeclampsia (1.4 times more common).
Risk of some of these outcomes appeared to be particularly elevated among women who had been exposed to a higher dose of DES or who had been exposed earlier in their mother’s pregnancy.
By the age of 55, 1 in 25 DES daughters will develop abnormal cellular changes in the cervix or vagina as a result of DES exposure, and 1 in 50 will develop breast cancer as a result of DES exposure.
These results provide additional information about the cancer and reproductive risks experienced by DES daughters. Researchers will continue to follow these women as they age. Separate studies are being conducted of boys who were exposed to DES before birth. Thus far, DES-exposed boys do not appear to have decreased fertility.
People who were exposed to DES before birth should be aware of the possible health effects and should inform their doctor about their DES exposure.
Reference: Hoover RN, Hyer M, Pfeiffer RM et al. Adverse health outcomes in women exposed in utero to diethylstilbestrol. New England Journal of Medicine. 2011;365:1304-14.
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